Hydrogen is expected to be a primary energy source in the 21st century for electricity generation, fuel and other applications. It is an environmentally clean energy source since it generates no pollutants. Fossil fuels and water are the major sources for the manufacture of hydrogen. However, these processes are highly energy intensive consuming nearly twice as much as energy from these sources and not always environment-friendly. Moreover, the fossil-fuel (mainly petroleum) reserves of the world are depleting at an alarming rate. The electrolysis of water so far is the cleanest way but the theoretical over-potential required to oxidize water is −1.23 V versus SHE (standard hydrogen electrode).
Coal which is considered as the cheapest source of energy available on earth, can be a potential solution to confront the issues associated with the electrolysis of water, we propose to demonstrate and study the feasibility of continuously electrolyzing Ohio coal to produce hydrogen for fuel cell applications. The reversible thermodynamic potential of the oxidation of coal is only −0.21 V which is much less when compared to conventional water electrolysis, thus making coal slurry electrolysis more competitive.
Coughlin and Farooque reported the equations (3)-(5).1-3 The authors found that the current efficiency for the production of hydrogen was 100%. These researchers reported that coal slurry needs to strike the electrode, which means that the reaction involves the solid and not only the liquid.1-3 
Other researchers performed additional studies to have a better understanding of the electro-oxidation. Baldwin et al.4 analyzed the fundamental electrochemical behavior of coal slurries using voltammetry techniques. Different slurry samples were prepared with bituminous Kentucky coals (Kentucky Institute for Mining and Minerals Research): No. 9 Seam, No. 11 Seam, Sterns No. 2 Seam, Elkhorn No. 3 Seam, and one anthracite coal sample (ICH-13) from the Buck Mountain seam from Zerbe, Pa. The electrochemical cell (batch cell) consisted of a three electrode arrangement, with Pt gauze as the working and counter electrodes and SCE as the reference electrode. The electrolyte solution for the cathode compartment was H2SO4, and LiClO4 was used for the anode compartment. The authors do not present an explanation of why they used LiClO4. The solutions were deoxygenated with N2 prior to use. All of the slurries were 2% weight concentration. The authors4 found much lower currents than the ones reported by Coughlin and Farooquel1-3 (10 times lower) and they attributed this behavior to the types of coal utilized, coal slurry concentration, electrode area, and reaction temperature employed. However, the electrolyte that they used is different and this may have affected their results. An important finding by the authors is that they reported that the activity of the system is in the extracted solution and not in the slurry. This finding is in some sense contradictory with what Coughlin and Farooque observed.1-3 These researchers reported that coal slurry needs to strike the platinum electrode, which means that the reaction involves the solid and not only the liquid.1-3 
Dhooge et al.5 tried to elucidate the mechanisms associated with the electrolysis of coal. For their experiments, the authors used a coal sample from the San Juan Valley, northwestern New Mexico (44.81% C, 3.91% H, 0.47% N, and about 33% ash content). The most important finding of this paper5 is that they proposed a mechanism for the electro-oxidation of coal that seems to be in agreement with the observations reported by Coughlin and Farooque.1-3 According to the authors Fe+3 acts as a catalyst, which is oxidized to Fe+2 on the coal according to the chemical reaction:5 4Fe+3+C+2H2O→4Fe+2+CO2+4H+  (1)The reduction of Fe+3 to Fe+2 is spontaneous, but it needs to happen at a surface, in this case the surface is the coal (which is oxidized). This means that the slurry needs to be present. On the other hand, Fe+3 is regenerated at the anode electrode according to the reaction:Fe+2→Fe+3+e−  (2)If only the filtrate is used, Fe+2 would not be regenerated. This explains why Coughlin and Farooque could run their experiments for a long time without a decrease in the current.1-3 One point that the authors of this paper do not analyze is the statement made by Coughlin and Farooque that the slurry (including the solids) needs to be in contact with the working electrode.1-3 Our explanation for this is that this is probably due to the fact that the concentration of Fe+3 species (regenerated at the working electrode) is higher next to the electrode. Another important finding from Dhooge et al.5 is the catalytic effect of Ce+4.
However, none of the authors1-10 were able to develop catalysts that enhance the oxidation of coal and they didn't combine the catalytic effect of Fe+3/Fe+2 for the production of hydrogen which is disclosed in this invention. Furthermore, they were not able to build a continuous cell for the electrolysis of coal. For example, the studies available in the open literature reported only small current densities (maximum of 8 mA/cm2 calculated using geometric area of electrode) achieved at voltages of up to 1.0 V and operating temperatures of 80° C.1-10.